He speaks invalid things

Job 24:25  And if it be not so now, who will make me a liar, and make my speech nothing worth?

He who speaks lies

Pro 19:22  The desire of a man is his kindness: and a poor man is better than a liar

He gives ear to a naughty tongue

Pro 17:4  A wicked doer giveth heed to false lips; and a liar giveth ear to a naughty tongue.

He adds unto the Word of God

Pro 30:6  Add thou not unto his words, lest he reprove thee, and thou be found a liar.

The one who doesn't fulfill what he said

Jer 15:18  Why is my pain perpetual, and my wound incurable, which refuseth to be healed? wilt thou be altogether unto me as a liar, and as waters that fail?

He speaks things of his own

Joh 8:44  Ye are of your father the devil, and the lusts of your father ye will do. He was a murderer from the beginning, and abode not in the truth, because there is no truth in him. When he speaketh a lie, he speaketh of his own: for he is a liar, and the father of it.

The one who disowns the Father

Joh 8:55  Yet ye have not known him; but I know him: and if I should say, I know him not, I shall be a liar like unto you: but I know him, and keep his saying.

He who is not God (Man is a liar)

Rom 3:4  God forbid: yea, let God be true, but every man a liar; as it is written, That thou mightest be justified in thy sayings, and mightest overcome when thou art judged.

He disowns sin

1Jn 1:10  If we say that we have not sinned, we make him a liar, and his word is not in us.

He keepeth not his commandments

1Jn 2:4  He that saith, I know him, and keepeth not his commandments, is a liar, and the truth is not in him.

He that denieth that Jesus is the Christ

1Jn 2:22  Who is a liar but he that denieth that Jesus is the Christ? He is antichrist, that denieth the Father and the Son.

He hateth his brother

1Jn 4:20  If a man say, I love God, and hateth his brother, he is a liar: for he that loveth not his brother whom he hath seen, how can he love God whom he hath not seen?

He doesn't believe in God

1Jn 5:10  He that believeth on the Son of God hath the witness in himself: he that believeth not God hath made him a liar; because he believeth not the record that God gave of his Son.